2. 0 1 3 2
4 5 7 6

5. At Time T= 0nS, B=C=1, and
6nS, B= 0, C=1, and
hence the output “BC” must be
changed from ‘0’ to ‘1’ after ??
‘1’ ‘0’

7. At Time T= 7nS, B’= 1, A=1, and
At Time T=output “ AB’ ” must be
henceTime 0nS, B’= B’= 0, A=1, and
At the T= 1nS, 1, A=1, and
hence the the?? “ AB’AB’ ” must be
______________ output “ ” must be
hence output
______________?? ??
______________

8. At Time T= 2nS, BC= 1, AB’=1,
9nS,
8nS,
3nS, 0, AB’=0,
and hence the output “ AB’ + BC ”
must be ______________??

9. Time A B C F
0nS 1 1 1 1
6nS 1 0 1 1

10. Hazards
When the input to a combinational circuit changes,
unwanted switching transients (hazards) may appear in
the output.
These transients occur when different paths from
input to output have different propagation delays.

11. Types of Hazards
°Static 1-hazard
a circuit output may momentarily go to 0
when it should remain at constant 1
Static 0-hazard
a circuit output may momentarily go to 1
when it should remain at constant 0
°Dynamic hazards
a circuit output may change 3 or more
times when it should change from 0 to 1 (or 1 to 0)